Re: [Haskell-cafe] On the verge of ... giving up!
Hello Vimal, Sunday, October 14, 2007, 2:44:05 PM, you wrote: Dear Haskellers, I have been trying my best to read about Haskell from the various first time when i tried to learn haskell i give up and returned only a year later :) about IO: you may try to read http://haskell.org/haskellwiki/IO_inside -- Best regards, Bulatmailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
On 10/19/07, Valery V. Vorotyntsev [EMAIL PROTECTED] wrote: On 10/19/07, Johan Tibell [EMAIL PROTECTED] wrote: If you have a web server somewhere you can use CGIIRC. That's what I did in a similar situation. http://cgiirc.org/ Thanks, Johan! There is one at http://ircatwork.com/ And now I'm in. Thank you very much. :) -- vvv ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
On 10/19/07, Valery V. Vorotyntsev [EMAIL PROTECTED] wrote: On 10/18/07, Don Stewart [EMAIL PROTECTED] wrote: Please drop by the irc channel! enthusiasm is always welcome there, and we're pretty much all obsessed too! Maybe that's not The Right Thing(TM) to ask, but anyway. :) My access the world outside the office's LAN is limited to ports 80 and 443. And chat.freenode.net lives on 6667. Once upon a time I could access #haskell via IRC gateway @ irc.e.jabber.ru, but not know, for the reasons unknown. Do you know of any 443:server, forwarding connections to chat.freenode.net:6667? Thanks a lot. If you have a web server somewhere you can use CGIIRC. That's what I did in a similar situation. http://cgiirc.org/ -- Johan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
On 10/18/07, Don Stewart [EMAIL PROTECTED] wrote: Please drop by the irc channel! enthusiasm is always welcome there, and we're pretty much all obsessed too! Maybe that's not The Right Thing(TM) to ask, but anyway. :) My access the world outside the office's LAN is limited to ports 80 and 443. And chat.freenode.net lives on 6667. Once upon a time I could access #haskell via IRC gateway @ irc.e.jabber.ru, but not know, for the reasons unknown. Do you know of any 443:server, forwarding connections to chat.freenode.net:6667? Thanks a lot. -- vvv ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
On Wed, 17 Oct 2007 21:59:41 +0100 Andrew Coppin [EMAIL PROTECTED] wrote: Well anyway, as you can see, I'm back. Mainly because I have questions that I need answers for... Welcome back ;) This mailing list is the only place I know of that is inhabited by people who actually think Haskell is something worth persuing. Huh, the above is grievous offence to #haskell :-) Sincerely, Gour signature.asc Description: PGP signature ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
On Thu, 18 Oct 2007, [EMAIL PROTECTED] wrote: Felipe Lessa writes: On 10/17/07, Andrew Coppin [EMAIL PROTECTED] wrote: ... And it frustrates the hell out of me that 100% of the human population consider Haskell to be an irrelevant joke language. ... I feel this way as well, specially because one of the teachers here tell all students that Haskell is the slowest thing ever by comparing Fibonacci sequence implementations between C and Haskell *using Hugs*. We shall thus understand that a teacher who likes Fibonacci, is a representant of of the 100% of the human population. Uh, Jerzy? You might want to consider this a variant of the idiomatic nobody cares, which also isn't quite meant literally. -- [EMAIL PROTECTED] A problem that's all in your head is still a problem. Brain damage is but one form of mind damage. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
Brent Yorgey wrote: Well anyway, as you can see, I'm back. Mainly because I have questions that I need answers for... glad you're back. =) This mailing list is the only place I know of that is inhabited by people who actually think Haskell is something worth persuing. don't forget about the IRC channel! That have talking on IRC now? ...damn it. That was an opinion... OK, I'll try harder in future. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
andrewcoppin: Hugh Perkins wrote: You're picking on Andrew Coppin? That's insane. He's got a sense of humour, and he's a lay (non-phd) person. Honestly, in one thread you've got Haskell is misunderstood! Its the greatest language in the world! Why does no-one use it and in another you're insulting one of the few non-phds who's interested in the language. Um... well... thanks for the unsolicited defence. Well anyway, as you can see, I'm back. Mainly because I have questions that I need answers for... For what it's worth, I think Haskell is the most fantastic programming language ever invented. I spend all my time thinking about it and using it. And it frustrates the hell out of me that 100% of the human population consider Haskell to be an irrelevant joke language. So I basically have this uncontrollably awsome thing in front of me that I spend all my time and energy interacting with... and nobody to talk to about it. This mailing list is the only place I know of that is inhabited by people who actually think Haskell is something worth persuing. However, apparently even here my enthusiasm is misplaced. Please drop by the irc channel! enthusiasm is always welcome there, and we're pretty much all obsessed too! -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
Hugh Perkins wrote: You're picking on Andrew Coppin? That's insane. He's got a sense of humour, and he's a lay (non-phd) person. Honestly, in one thread you've got Haskell is misunderstood! Its the greatest language in the world! Why does no-one use it and in another you're insulting one of the few non-phds who's interested in the language. Um... well... thanks for the unsolicited defence. Well anyway, as you can see, I'm back. Mainly because I have questions that I need answers for... For what it's worth, I think Haskell is the most fantastic programming language ever invented. I spend all my time thinking about it and using it. And it frustrates the hell out of me that 100% of the human population consider Haskell to be an irrelevant joke language. So I basically have this uncontrollably awsome thing in front of me that I spend all my time and energy interacting with... and nobody to talk to about it. This mailing list is the only place I know of that is inhabited by people who actually think Haskell is something worth persuing. However, apparently even here my enthusiasm is misplaced. I'm getting rather tired of being repeatedly flamed. So, in the interests of preventing any further incidents, I will limit myself to only asking specific questions that solicit a specific answer, and I will attempt to refrain from stating any opinion of any kind. Hopefully that way at least I'll get something useful from this list, and the other people reading it won't have to listen to me being flamed again... [Let the lurking begin...] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
Well anyway, as you can see, I'm back. Mainly because I have questions that I need answers for... glad you're back. =) This mailing list is the only place I know of that is inhabited by people who actually think Haskell is something worth persuing. don't forget about the IRC channel! -Brent ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
On 10/17/07, Andrew Coppin [EMAIL PROTECTED] wrote: it. And it frustrates the hell out of me that 100% of the human population consider Haskell to be an irrelevant joke language. So I basically have this uncontrollably awsome thing in front of me that I spend all my time and energy interacting with... and nobody to talk to about it. This mailing list is the only place I know of that is inhabited by people who actually think Haskell is something worth persuing. However, apparently even here my enthusiasm is misplaced. I feel this way as well, specially because one of the teachers here tell all students that Haskell is the slowest thing ever by comparing Fibonacci sequence implementations between C and Haskell *using Hugs*. Unfortunately he doesn't want to now GHC or anything else that changes his mind. But it's easy to impress your friends. One of these days I used Parsec to solve in 5 minutes a problem most people had spent at least a couple of hours. And besides having one tenth of SLOC, it gave nice error messages. They're getting interested, and some of them already said that they'll learn it on the next summer (we're on the Southern Hemisphere =). Someday we'll be using monads on e-mails. Maybe this is not the best way to present a language, but in a university where most people think that Java is the answer for every question, it's the way I found to motivate them. Oh, and I'm an undergraduate. Do I get free lambdas? :) PS: Does anybody have slides for teaching imperative programmers how to start feeling Haskell? I would like to give them a sort of minicourse for getting started. -- Felipe. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
Felipe Lessa writes: On 10/17/07, Andrew Coppin [EMAIL PROTECTED] wrote: ... And it frustrates the hell out of me that 100% of the human population consider Haskell to be an irrelevant joke language. ... I feel this way as well, specially because one of the teachers here tell all students that Haskell is the slowest thing ever by comparing Fibonacci sequence implementations between C and Haskell *using Hugs*. We shall thus understand that a teacher who likes Fibonacci, is a representant of of the 100% of the human population. On the other hand, Microsoft Research who pays some developers of Haskell (whose names I have forgotten) doesn't count at all. Very interesting. Jerzy Karczmarczuk ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
On 10/17/07, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: We shall thus understand that a teacher who likes Fibonacci, is a representant of of the 100% of the human population. Sorry if I didn't understand very well the tone of your message or if I wasn't clear enough, however what I was trying to say is that he makes up the mind of most of his students with the idea that Haskell is a toy language with poor performance and strange limitations. IOW, that it's difficult to breath Haskell there. Let's try not to start another meaningless discussion here, please =). Cheers, -- Felipe. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
Felipe Lessa writes: On 10/17/07, [EMAIL PROTECTED] We shall thus understand that a teacher who likes Fibonacci, is a representant of of the 100% of the human population. Sorry if I didn't understand very well the tone of your message or if I wasn't clear enough, however what I was trying to say is that he makes up the mind of most of his students with the idea that Haskell is a toy language with poor performance and strange limitations. My tone was obviously sarcastic, and the reason is that for ANY niche of human activity you may find lousy teachers. And - in my eyes - you shouldn't have agreed on such a pathological example that 100% of the human population consider Haskell a toy. Haskell is being taught in hundreds of places. That's all. We shouldn't advertize bad teachers. BTW., almost 100% of humanity don't care at all about the General Theory of Relativity. And *never did*. It didn't prevent Einstein from sleeping. Of course, this example is as silly as it is, but not more. J.K. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
i fear that, at this point, this thread is a test: if I post a reply, it shows that I am a fool. ah well. JK, of course there are foolish teachers out there. I don't think Felipe was suggesting that this teacher had the right idea, nor that he himself was going to stop haskelling anytime soon. But when people in relative power say wrong things, it makes it harder for junior colleagues (or students) to establish credibility, with other colleagues and students. You may be of the opinion that such colleagues and students are fools, or beyond help. But I think none of us made it to the promised land of haskell in a vacuum - most were introduced by a friend or teacher. Seems to me that Felipe feels a little thwarted in his desire to pass on the favor to others. Your tone suggests that it's some kind of moral weakness to want others to get what we're talking about, what I'd call the what do you care what other people think? philosophy. Of course, such a mindset can be very valuable, and we should all cultivate self-confidence. Nevertheless, I think there's no shame in wanting other people to share in our joy - many of us are on this email list because we are mini-evangelists as well as lovers of haskell. on the whole, I think we evangelists can be a good thing for haskell, though of course we must be responsible scholars ourselves. It's not clear to me that Einstein slept so well (for myriad reasons), and one can easily point to people who were geniuses and visionaries, who were miserable for much of their life (Cantor, Godel, Turing, etc). Aren't we all, to some degree, interested in creating a world where our ideas get more support? You mention MS Research supporting the Simons - well, MSR does so in part because both of them (and their colleagues at MSR Cambridge) are tireless evangelists, who are fantastically generous with their time, ideas, and code. One way to go might be to code haskell in self-confident semi-secrecy, and demonstrate the wonderfulness of our ideas by the results it produces. This would be great. Another way to go is to teach others what is *already* known. I think we can all agree that today there is a vast gulf between what is considered good, professional programming, and what is the state of the art in CS (and specifically PL theory) today. Hence I suspect that the good fight can be fought on many fronts at the same time. On Thu, 18 Oct 2007, [EMAIL PROTECTED] wrote: Felipe Lessa writes: On 10/17/07, [EMAIL PROTECTED] We shall thus understand that a teacher who likes Fibonacci, is a representant of of the 100% of the human population. Sorry if I didn't understand very well the tone of your message or if I wasn't clear enough, however what I was trying to say is that he makes up the mind of most of his students with the idea that Haskell is a toy language with poor performance and strange limitations. My tone was obviously sarcastic, and the reason is that for ANY niche of human activity you may find lousy teachers. And - in my eyes - you shouldn't have agreed on such a pathological example that 100% of the human population consider Haskell a toy. Haskell is being taught in hundreds of places. That's all. We shouldn't advertize bad teachers. BTW., almost 100% of humanity don't care at all about the General Theory of Relativity. And *never did*. It didn't prevent Einstein from sleeping. Of course, this example is as silly as it is, but not more. J.K. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
The really amazing thing about the IO Monad in Haskell is that there *isn't* any magic going on. An level of understanding adequate for using the I/O and State monads stuff (that is, adequate for practically anything analogous to what you might do in another language) goes like this:[...] Yes, I am at the stage where I can understand most of whats going on, as you described it in your email. I was wondering if understanding Category Theory would help me model situations better. Thats all :) But for now, I guess I will stick with this. Assuming that its a black box and it does what its supposed to do. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up! [OT]
Richard A. O'Keefe writes: (2) The mathematical background of Haskell is extremely important for implementations. Some important data structures and techniques are practical in large part because of the kinds of optimisations that are only straightforward in a language that has such foundations. (3) Beginners do not need to understand all the mathematics behind Haskell to use it. (5) Precisely because it seeks generality, category theory seems difficult to concrete thinkers. And books on category theory tend to be extremely fast-paced, so ideas which are not in themselves particularly esoteric (which may in fact be eminently practical) tend to be presented in a way which people trying to study by themselves have trouble with. So people can be scared off by what _ought_ to be a big help to them. Yes. Yes. And when *additionally* people whose experience/competence is rather weak, spread the fear, hatred and carelessness, I have the impression that this is something similar to a guy in primary school (and this list *is* a kind of school) who bothers the pupils with such discoveries as the differential calculus is a swearword, just to annoy you, you will =never= need that, I live happily without. There IS a problem. The fast pace of Category theory is a bit incomplete diagnosis. For me, what was most annoying was an awful trap. Everything began slowly, and nicely. And authors are kind, helpful, and understanding. And they promise that it is *for me*. Or for Brandon S. Allbery KF8NH... (BTW, Why Andrew Bromage says that the book of Lawvere is pricey? Cambridge Univ. Press sells the Conceptual Mathematics for 33 pounds. This is not so much...) Check some other titles, *free*, please: *Categories for =working comp. sci'ists=, AspertiLungo. *Categorical Primer by Chris Hillman (he - apparently - still revises the next version...) *Gentle introduction to Cat. Th., a calculational approach by Fokkinga. *Basic Cat., by Jaap Van Osten, a course for undergraduates, which begins by saying that for the Author the basic experience counts more than theory. (And, of course, Barr and Wells...) Now, you start reading, it goes smoothly, you understand functors, natural transformations, retracts, initial objects, etc. And then the slope begins to increase exponentially, you hit a wall... It seems that people who finally decided to write books, tutorials, etc. are so conditioned, that they cannot put themselves into a skin of a true profan, even people so perfect, so didactically skilled as Barr and Wells. But as says the quotation from a science-fiction story /Born among the dead/: you must elevate yourself to their level, since you cannot force them to descend to yours... Still, monads, Kleisli triples, etc. belong to the *EASY* part!! === So, if some people really *want* to learn something, some time devote they shall. But, there are some shortcuts as well, although nothing complete. http://en.wikibooks.org/wiki/Haskell/Category_theory is a nice introduction! The paper on Bananas, lenses and barbed wire (Meijer, Fokkinga, Paterson) is almost a compulsory reference. The craziness of generalization/universality is very well exposed in the compilation of Fritz Ruehr, which can be read by *ANYBODY*. There is no hard science inside, just examples! http://www.willamette.edu/~fruehr/haskell/evolution.html Once upon a time, Eric Meijer and Luc Duponcheel wrote a paper entitled On the expressive power of constructor classes, where they proposed a new categorical prelude for Gofer. It is an extremely inspiring paper! (Citeseer shall have it.) Some of ideas therein, in a different setting, can be easily read in the Varmo Vene thesis on coinduction, and other horrible stuff. And, of course, there is a paper by Conor McBride and Ross Paterson on applicative programming with effects, with an interesting discussion *around* monads. http://www.soi.city.ac.uk/~ross/papers/Applicative.pdf ... Ugh. I am afraid I began an infinite, corecursive strem. Perhaps it is time to break it. Jerzy Karczmarczuk ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up! [OT]
On Oct 15, 2007, at 7:01 , Yitzchak Gale wrote: But I think we are still at the stage where a programmer who wants practical results is better off starting out by learning how to use monads in practice, not by delving into category theory. No argument from a Haskell standpoint. Still, when people here or on #haskell start tossing CT around, it'd be nice to have more than a very vague and probably incorrect notion of what they're saying. :) -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] [EMAIL PROTECTED] system administrator [openafs,heimdal,too many hats] [EMAIL PROTECTED] electrical and computer engineering, carnegie mellon universityKF8NH ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] On the verge of ... giving up!
Dear Haskellers, I have been trying my best to read about Haskell from the various tutorials available on the internet and blogs. I havent been following YAHT properly, so its always been learning from 'bits and pieces' scattered around. For most languages (like C/C++/Ruby/Python), the above approach has helped me. But for Haskell, it is failing. I like learning by comparison with other similar languages. This approach worked for me when I tried learning Python+Perl together. The nicer syntax and easier object-orientedness made me leave Perl behind and pursue Python. I also tried it for Haskell (Lisp+OCaml+Haskell together). The next step I usually take in learning a language is, not to go by the topics found in textbooks, but by taking real world examples and then blindly try to solve it using that language as a tool. For e.g, I tried writing a terminal GTalk client for Python when I was learning it, and learnt so many features that way. I used to call this 'learning by need', and it worked, to the extent that I never knew how to take 'input' from the user, but knew how to write Objects in Python! (Since I never used input in that example :) I didnt want to repeat that mistake, so I made sure I would learn IO in Haskell, which initially turned out to be a disaster, due to the 'Moands' which sounded like 'Go Mads' to me. Then, I set out to learn Monads + Category Theory from a Math perspective. And since I haven't been introduced to abstract math (like Groups, etc.), I found this a little difficult. However I tried my best to understand the tiniest bit and waited for the tiniest spark that would enlighten me. It didn't work out. --snip-- Okay, so you might be wondering as to whats the whole point of this mail? Well, I am almost on the verge of giving up on something I really like to learn, just because I didn't go in the right order! So, I requested my institute to buy Dr. Graham Hutton's book. I would be getting hold of that quite soon, and am willing to start from the beginning. Meanwhile, could anyone suggest if there was anything wrong in my approach to learning Haskell/the other languages? I agree that the learning methodology is something personal and I have to find out what best suits me, but I would like to hear something from you, Haskellers, too. I have no need to hurry anything at this point of time. But after being introduced to the tiniest bit of Haskell, and after seeing such a large and active community here, and #haskell, I had the plan of conducting a Haskell Workshop, in our department (sometime in Feb next year, the dates have not been finalized). I just hope that I should be able to reach a substantial amount of familiarity with Haskell by that time! Sorry for the long mail, and pardon me if it was too boring. I just put my thoughts on strikepaper/strike a mail :) I did have a couple of ambitious projects in my mind when to help me learn Haskell. They were: 1. An online judge system (Like http://spoj.pl). I had already done one for contests that were held during our Technical festival here, using php. The ideas are laid out. All I had to focus on was learning Haskell. 2. A solver for the Peg-Solitaire. This was more of an academic interest. I have seen Richard Bird's presentation on 'How to write a functional pearl, with an example' and was quite impressed by it. But the actual modelling might be slightly tricky here, and I am yet to start off with it. Many thanks for your patience, Cheers, -- ~Vimal IIT Madras RLE :) encode = map (length head) . group decode = concatMap (uncurry replicate) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
Hi Then, I set out to learn Monads + Category Theory from a Math perspective. This is where you went wrong. I know none of this stuff and am perfectly happy with IO in Haskell. Read http://www.haskell.org/haskellwiki/Monads_as_Containers and then read lots of other Monad tutorials for Haskell. So, I requested my institute to buy Dr. Graham Hutton's book. I would be getting hold of that quite soon, and am willing to start from the beginning. I'm not sure this covers IO in any great detail - it will be useful for general Haskell though. 1. An online judge system (Like http://spoj.pl). I had already done one for contests that were held during our Technical festival here, using php. The ideas are laid out. All I had to focus on was learning Haskell. 2. A solver for the Peg-Solitaire. This was more of an academic interest. I have seen Richard Bird's presentation on 'How to write a functional pearl, with an example' and was quite impressed by it. But the actual modelling might be slightly tricky here, and I am yet to start off with it. I would try number 2 first. IO in Haskell can be tricky, especially while you are learning all the other bits of the language at the same time. Network stuff is also not as well developed in terms of libraries as something like Python - but something like HappS should be able to do a spoj clone easily enough. A better choice for an initial IO application might be something like du, then moving to an online judge system later on. Thanks Neil ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
Vimal wrote: I like learning by comparison with other similar languages. This approach worked for me when I tried learning Python+Perl together. The nicer syntax and easier object-orientedness made me leave Perl behind and pursue Python. I also tried it for Haskell (Lisp+OCaml+Haskell together). This probably works quite well for mainstream programming languages (since they're all so similar), but is unlikely to work at all for Haskell (since, as far as I know, no other programming language on Earth is remotely like it - Miranda excluded). Even Lisp and Erland are nothing like Haskell, and they're supposedly based on the same ideas. The next step I usually take in learning a language is, not to go by the topics found in textbooks, but by taking real world examples and then blindly try to solve it using that language as a tool. Not a bad way to learn to use a tool. You might want to stick to things that involve simple I/O and complex processing rather than the other way round though. ;-) (For example, I wrote a program that renders an animation of the solutions of a simple differential equation by numerical integration. The math is complex; the I/O just involves dumping millions of numbers into a big text file.) I didnt want to repeat that mistake, so I made sure I would learn IO in Haskell, which initially turned out to be a disaster, due to the 'Moands' which sounded like 'Go Mads' to me. For the longest time I couldn't remember whether it's monad or monand... but anyway, yeah, it's a common problem. It's not actually complicated ones you understand it; it's just that it's so abstract that it's hard to explain. It's a bit like trying to explain to somebody what a magnet is... it's not a complex concept, just hard to describe. Then, I set out to learn Monads + Category Theory from a Math perspective. Um... yeah, that probably won't work. As far as I know, Haskell's idea of monad has little to do with the theoretical concept. Meanwhile, could anyone suggest if there was anything wrong in my approach to learning Haskell/the other languages? I agree that the learning methodology is something personal and I have to find out what best suits me, but I would like to hear something from you, Haskellers, too. I'm a maths nerd. To me, Haskell looks like an advanced term-rewrite system similar to Mathematica. It was quite easy to learn the basics. What took longer was learning to approach problems in the right way. The way you'd do things in an object oriented language is usually NOT the way you'd do it in Haskell. (Unless you enjoy making your life hard...) Unfortunately, that's all practice. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
Hi Vimal I didnt want to repeat that mistake, so I made sure I would learn IO in Haskell, which initially turned out to be a disaster, due to the 'Moands' which sounded like 'Go Mads' to me. Then, I set out to learn Monads + Category Theory from a Math perspective. And since I haven't been introduced to abstract math (like Groups, etc.), I found this a little difficult. However I tried my best to understand the tiniest bit and waited for the tiniest spark that would enlighten me. It didn't work out. In my opinion (other may think differently) it is not a good idea to learn IO by starting with trying to grasp the theoretical foundation for monads. In the beginning you should just view the IO monad as Haskell's way of doing imperative IO stuff. When you feel comfortable with Haskell IO, then try to learn a couple of other monads. Then maybe this article http://sigfpe.blogspot.com/2006/05/grok-haskell-monad-transformers.html about monad transformers. It is good because it do not try to explain the implementation details of monad transformers - just how you use them. When you have done all that, then you should be ready for all the details. --snip-- Okay, so you might be wondering as to whats the whole point of this mail? Well, I am almost on the verge of giving up on something I really like to learn, just because I didn't go in the right order! So, I requested my institute to buy Dr. Graham Hutton's book. I would be getting hold of that quite soon, and am willing to start from the beginning. Meanwhile, could anyone suggest if there was anything wrong in my approach to learning Haskell/the other languages? I agree that the learning methodology is something personal and I have to find out what best suits me, but I would like to hear something from you, Haskellers, too. As I wrote above, I think you are trying to understand too many details at once. Also a textbook can sometimes be helpful. But you also have a learning by doing approach, which I personally find very productive. And do not give up yet. Haskell has a lot to offer and I think it is well worth the steep learning curve. Cheers, Mads Lindstrøm ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
I just started working in Haskell about 2-3 months ago, and I'm loving it. I've programmed a lot in Scheme which I learned my freshman year in college, so that helped a lot with the difference between functional and oop languages, but as Andrew Coppin mentioned, Haskell is quite different even from Lisp/Scheme etc. By way of an annecdote, the other day, I was working on a problem in Haskell and having some problems getting types (I believe it was a problem of converting between different types of numbers) to match up correctly. Darnit, if I was doing this in Scheme, I thought, the types would just work themselves out, so I booted up DrScheme and started translating the code. It took me three times as long because of all the list comprehensions and laziness that I had started to use so automatically in Haskell. Anyway... let me get to some of your questions. So, I requested my institute to buy Dr. Graham Hutton's book. I would be getting hold of that quite soon, and am willing to start from the beginning. So when I first started with Haskell, I started with the online tutorials, but got stuck with the Monad stuff. So I actually ordered this same book and read it cover to cover, and it helped a quite a bit, but I still needed some practical experience. I think the examples which compare parsing strings to doing IO are especially instructive with respect to understanding Monads. However, what I'm really missing at this point is how to write my own monads. (As a side note, I'm not entirely convinced that you need to write a lot of your own monads, but I'd still like to understand that) The next step I usually take in learning a language is, not to go by the topics found in textbooks, but by taking real world examples and then blindly try to solve it using that language as a tool. For e.g, I tried writing a terminal GTalk client for Python when I was learning it, and learnt so many features that way. I used to call this 'learning by need', and it worked, to the extent that I never knew how to take 'input' from the user, but knew how to write Objects in Python! (Since I never used input in that example :) I also agree about this, so I started looking for small projects on which to cut my teeth and really learn the basic concepts in Haskell well. Then I stumbled onto Project Euler (projecteuler.net). Its a whole bunch of math-related problems where you usually need to write a program to do some sort of search for numbers with specific properties or to find the number of combinations for some bizarre situation etc. It may or may not be your cup of tea in the sense that the problems themselves are a bit esoteric and you'll never use these programs again. However, I (have) found that: 1. These smaller exercises have really helped me learn some of the weirder syntax better (ex: list comprehensions are now a piece of cake) 2. A number of the exercises require you to come up with more than just a brute force search (or your program will take too long to produce an answer), so I've had to learn about various topics (ex: how to use arrays in a functional (non-imperitive) way to accomplish dynamic programming type tasks) 3. Haskell is ideally suited to doing mathy type problems. For example, the laziness feature of the language (something else that is entirely different from most main stream languages, and which I needed more practice with) allows me to implement (potentially) infinite searches in the same way as I implement finite searches. I didnt want to repeat that mistake, so I made sure I would learn IO in Haskell, which initially turned out to be a disaster, due to the 'Moands' which sounded like 'Go Mads' to me. A couple of my solutions to project euler required me to use hashtables (before I figured out how to use arrays functionally) so I've picked up a little of the IO stuff. Its... less than intuitive, and I avoid it at all costs... some of the problems have large input files. I parse them by hand into Haskell syntax to avoid making my program have to do IO. But you can definitly learn more about IO by doing it the sane/intended way. Haskell programs tend to be structured to restrict IO to the surface level of the program, and use purely functional ideas to solve the meat of the problem. This seems to be one of the major design features of the language. However, most widely-used programs (ex: web browsers, word processors, email programs, data bases, IDEs) tend to be 90% IO and 10% (or less) computation. This can make Haskell quite unweildy for solving these types of problems. On the otherhand, writing something like a compiler (which requires a small amount of IO - read a file(s), write results to a file - and a large amount of unseen computation - generating and optimizing code) is right up Haskell's alley. Then, I set out to learn Monads + Category Theory from a Math perspective. And since I haven't been introduced
Re: [Haskell-cafe] On the verge of ... giving up!
David Stigant wrote: Haskell programs tend to be structured to restrict IO to the surface level of the program, and use purely functional ideas to solve the meat of the problem. This seems to be one of the major design features of the language. Yep, that's the idea. :-D However, most widely-used programs (ex: web browsers, word processors, email programs, data bases, IDEs) tend to be 90% IO and 10% (or less) computation. This can make Haskell quite unweildy for solving these types of problems. On the otherhand, writing something like a compiler (which requires a small amount of IO - read a file(s), write results to a file - and a large amount of unseen computation - generating and optimizing code) is right up Haskell's alley. Au contrare... ;-) Let us examine web browser for a moment. Yes, it does some input (typically fetching resources by HTTP), and some output (mainly displaying stuff on your screen). But wait a moment there... For a typical web page, you might well have to perform all of the following operations: - Parse an XHTML file into a document tree. (That's pretty algorithmic.) - Parse multiple CSS style sheets, and apply them to the document. (This involves processing possibly-complex element selectors, observing inheritance relationships, and merging the properties from several sources into a single result set. That's A LOT of algorithm!) - Parse some JavaScript and execute it. (That's an entire programming language, remember.) Watch in horror is it uses the DOM to *modify* the XHTML data you just parsed and applied CSS to... - Load several JPEG files. (You might think that load a JPEG file is I/O, but really, getting the data into memory is just the beginning. You've got a file to parse, you've got an arithmetic code to decompress, and then you've got an inverse Discrete Cosine Transform to do. Again, LOTS of algorithm.) - Let us hope to God the page doesn't contain any SVG... (Think of the massacre!) - Perform final layout (frames, tables, justification, backgrounds, transparency...) and rendering to incorporate all this data into one huge bitmap that can be dumped into the framebuffer. OK, so if you wrote this program today, the JPEG part would probably be an external library. And SVG, if you supported it. But you get the point; there is A LOT of heavily algorithmic stuff happening there that has little or nothing to do with I/O. The browser is sucking in XHTML, CSS, JavaScript, JPEG, SVG and God only knows what else (XSLT, anyone?), doing a mountain of processing with it, and only then showing the final result on your computer screen. There's a lot more I/O than your typical compiler, but don't go thinking there's nothing algorithmic happening here. ;-) Similarly, any good word processor is going to have layout algorithms (would you like that left-justified or right-justified? what happens if you have several typeface sizes in the same block of text? how does text flow round images?), and possibly cross-referencing. Email programs need to efficiently store and retrieve user's mail, and often have search facilities (and even Baysian filters for eliding spam). Even a humble IDE usually has syntax recognition... So you see, they may not spend quite as much *time* on computation as a compiler does, but there's still plenty of *complexity* there. ;-) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
Cool! Lots of opinion. Let me consider them one by one: @Neil: This is where you went wrong. I know none of this stuff and am perfectly happy with IO in Haskell. Read http://www.haskell.org/haskellwiki/Monads_as_Containers and then read lots of other Monad tutorials for Haskell. I tried this too, and this made some sense to me in the beginning. But, not enough to satisfy my curiosity! So, I tried to dig in ... So, I requested my institute to buy Dr. Graham Hutton's book. I would be getting hold of that quite soon, and am willing to start from the beginning. I'm not sure this covers IO in any great detail - it will be useful for general Haskell though. IO isnt the only problem. Monads + how to define your own Monads etc. Since Monad's arent just for IO, where else could it be used? (e.g. Stateful functions), but is that it? Is it possible for me to come up with an instance of a Monad to solve _my_ problem? Thats the kind of question I would like to answer :) I would try number 2 first. IO in Haskell can be tricky, especially while you are learning all the other bits of the language at the same time. Network stuff is also not as well developed in terms of libraries as something like Python - but something like HappS should be able to do a spoj clone easily enough. A better choice for an initial IO application might be something like du, then moving to an online judge system later on. You are probably right. Mimicking *nix tools might be great fun to start off with :) Thanks Thanks :) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
@Andrew: This probably works quite well for mainstream programming languages (since they're all so similar), but is unlikely to work at all for Haskell (since, as far as I know, no other programming language on Earth is remotely like it - Miranda excluded). Even Lisp and Erland are nothing like Haskell, and they're supposedly based on the same ideas. I didnt know this when I _started_ :) So, thats why I am learning Haskell in exclusion. Not a bad way to learn to use a tool. You might want to stick to things that involve simple I/O and complex processing rather than the other way round though. ;-) (For example, I wrote a program that renders an animation of the solutions of a simple differential equation by numerical integration. The math is complex; the I/O just involves dumping millions of numbers into a big text file.) Yes, as someone pointed out, Haskell was meant for a lot of computation, and IO is just a part of the story! For the longest time I couldn't remember whether it's monad or monand... but anyway, yeah, it's a common problem. It's not actually complicated ones you understand it; it's just that it's so abstract that it's hard to explain. It's a bit like trying to explain to somebody what a magnet is... it's not a complex concept, just hard to describe. But, being a computer science student, I think I need to look into it too! I like the quote found on this site: http://patryshev.com/monad/m-intro.html quote Monads in programming seem to be the most mysterious notion of the century. I find two reasons for this: * lack of familiarity with category theory; * many authors carefully bypass any mention of categories. It's like talking about electricity without using calculus. Good enough to replace a fuse, not good enough to design an amplifier. /quote I'm a maths nerd. To me, Haskell looks like an advanced term-rewrite system similar to Mathematica. It was quite easy to learn the basics. What took longer was learning to approach problems in the right way. The way you'd do things in an object oriented language is usually NOT the way you'd do it in Haskell. (Unless you enjoy making your life hard...) Unfortunately, that's all practice. Ah, I am not familiar with the term-rewrite you are talking about. I will Google it up then. Thanks :) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
In my opinion (other may think differently) it is not a good idea to learn IO by starting with trying to grasp the theoretical foundation for monads. In the beginning you should just view the IO monad as Haskell's way of doing imperative IO stuff. When you feel comfortable with Haskell IO, then try to learn a couple of other monads. Then maybe this article http://sigfpe.blogspot.com/2006/05/grok-haskell-monad-transformers.html about monad transformers. It is good because it do not try to explain the implementation details of monad transformers - just how you use them. When you have done all that, then you should be ready for all the details. Alright, this post seems interesting. Will try it out soon! As I wrote above, I think you are trying to understand too many details at once. Also a textbook can sometimes be helpful. But you also have a learning by doing approach, which I personally find very productive. Yeah, this has always been a problem with me. Its like browsing Wikipedia. Open an article, and you branch out like anything. Curiosity does kill the cat :( And do not give up yet. Haskell has a lot to offer and I think it is well worth the steep learning curve. Nope. I enjoy learning it, just waiting to hit the peak! Someone creative enough should draw the learning curve for Haskell :D. I remember some funny ones for text editors! (emacs had a spiral...) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
I think you have got a very good point in your mail that I overlooked all along ... Why was Haskell created? is a question that I havent tried looking for a answer :) I also agree about this, so I started looking for small projects on which to cut my teeth and really learn the basic concepts in Haskell well. Then I stumbled onto Project Euler (projecteuler.net). Its a whole bunch of Ah, yes, Project Euler. I did start doing this sometime back, but then gave up on it. Perhaps its time to start again :) Thanks, that was an eyeopener. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
Vimal wrote: Wikipedia. Open an article, and you branch out like anything. Curiosity does kill the cat :( Yeah, this has always been a problem with me. Its like browsing Whenever I do this, I usually end up reading about something utterly unrelated. (Actually, I usually end up reading about things which are toxic, explosive, flammable or corrosive... hmm, That's Not Good...) I tried to use Wikipedia to learn about how to build digital filters... this was a disaster. There is almost no useful information there! :-( ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
Vimal wrote: IO isnt the only problem. Monads + how to define your own Monads etc. Since Monad's arent just for IO, where else could it be used? (e.g. Stateful functions), but is that it? Is it possible for me to come up with an instance of a Monad to solve _my_ problem? Thats the kind of question I would like to answer :) I/O is a monad. Actually, there's another one called STM (for doing transactional modifications). And there are various ones for doing stateful stuff (e.g., incrimentally building a solution or something). Then there's the Maybe monad (for operations which sometimes fail). Lists are a monad (for operations that yield multiple results). Parsers are a celebrated example of monads - although the most efficient ones use something called arrows. (These are like monads, but even more abstract. If you enjoy making your head hurt...) There is also an entire zoo of other monads out there. There's a CPS monad (for writing unmaintainable code), many graphics libraries have a drawing monad... the list goes on. Is there any merit in you writing your own monad? Well, if it's doing something similar to existing monads, then maybe. (Note that there are such things as monad transformers, which allow you to merge multiple monads together into a giant, all-powerful monad. So, if you wanted a stateful parser that does I/O, you could use transformers to mix those exact features together - no coding required.) I would try number 2 first. IO in Haskell can be tricky, especially while you are learning all the other bits of the language at the same time. Network stuff is also not as well developed in terms of libraries as something like Python - but something like HappS should be able to do a spoj clone easily enough. A better choice for an initial IO application might be something like du, then moving to an online judge system later on. You are probably right. Mimicking *nix tools might be great fun to start off with :) Uh... think it's been done already. ;-) Still, you could try it yourself and see what you get - and then marvel at how others have done it in half the code. :-} ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
Vimal wrote: I think you have got a very good point in your mail that I overlooked all along ... Why was Haskell created? is a question that I havent tried looking for a answer :) To avoid success at all costs? (No, seriously. The basic idea was that there used to be about two-dozen languages like Haskell, but all developed by different people and all with different syntax and so on. So they wanted to create a single language suitable for teaching to students. You could say it's the Pascal of the functional world... Hey, maybe that explains the lack of success?) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
Vimal wrote: @Andrew: But, being a computer science student, I think I need to look into it too! I like the quote found on this site: http://patryshev.com/monad/m-intro.html quote Monads in programming seem to be the most mysterious notion of the century. I find two reasons for this: * lack of familiarity with category theory; * many authors carefully bypass any mention of categories. It's like talking about electricity without using calculus. Good enough to replace a fuse, not good enough to design an amplifier. /quote Maybe *this* is why I get nowhere with designing electronic things? I know very little about calculus. (And I can't begin to imagine what it has to do with electricity...) For what it's worth, a category is a class bearing some additional structure. A class is exactly like a set, except that all sets are classes, but only some classes are also sets. There *is* a reason for this, but nobody knows what it is. (They say it's because some classes are bigger than sets - which is absurd since a set can be of any size...) Ah, I am not familiar with the term-rewrite you are talking about. I will Google it up then. Thanks :) A term-rewrite system is just a system that replaces (rewrites) certain terms with other terms. For example, a package like Mathematica would have a term rewrite rule that says that all occurrances of x - x should be rewritten as 0. Haskell can't do anything quite *that* sophisticated, but what it *can* do is things like linear a b x = a*x + b which causes all terms involving linear to be rewritten into the thing on the RHS. You can actually draw the reduction sequence as an expression is transformed step by step into the final result: sum [1,2,3] foldr1 (+) [1,2,3] foldr (+) 1 [2,3] foldr (+) (1+2) [3] foldr (+) (1+2+3) [] 1+2+3 3+3 6 Each line is derrived from the previous one by some program rule. (The last three being hard-coded into the language itself.) If you're pathologically curiose, look up lambda calculus for a programming language like Haskell where the last few steps above are *definable* from first principles. :-D ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
On 10/14/07, Vimal [EMAIL PROTECTED] wrote: Dear Haskellers, I have been trying my best to read about Haskell from the various tutorials available on the internet and blogs. I havent been following YAHT properly, so its always been learning from 'bits and pieces' scattered around. You might try Erlang. It's easy like Python. It's designed for rock-solid enterprise applications. Threading and rpc are insanely easy. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
On 10/14/07, Vimal [EMAIL PROTECTED] wrote: IO isnt the only problem. Monads + how to define your own Monads etc. Since Monad's arent just for IO, where else could it be used? (e.g. Stateful functions), but is that it? Is it possible for me to come up with an instance of a Monad to solve _my_ problem? Thats the kind of question I would like to answer :) The approach I used to fully understand monads was the same as I used to fully understand Python's metaclasses: don't try to get into its inner until you need. I mean, don't try to find a problem to come up with a monad. Instead, someday you will going to solving a problem and you'll have the idea of making instance Monad of it. Meanwhile you'll get used to the language and see lots of other already-built monads. Well, worked for me. The beautiful thing about monads and metaclasses is that they are extremely simple after you understand them. That's also why monads are called Warm, fuzzy things, AFAICT =). But both don't fit everywhere, and it requires some experience to see that. -- Felipe. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
I will be impolite. Andrew Coppin says: For what it's worth, a category is a class bearing some additional structure. A class is exactly like a set, except that all sets are classes, but only some classes are also sets. There *is* a reason for this, but nobody knows what it is. (They say it's because some classes are bigger than sets - which is absurd since a set can be of any size...) If this were the first posting of A.C., I would suspect that he is pulling my leg, that his brilliant sense of humour surpasses my comprehension, so I should be filled-up with deep respect for such a wonderful mind. But enough is enough. Now, would it be really too much asking that - at least from time to time - Andrew Coppin think twice before saying things he - apparently - knows NOTHING about? Haskell café, is, well, café... even no tobacco restrictions. But, since we have here people who want to learn something structured and based on some real competence, saying e.g. that CPS monad is for making unmaintainable code, or I know very little about calculus. (And I can't begin to imagine what it has to do with electricity...), is becoming a nuisance. I skipped the postings of A.C., as most of people on this forum I happen to know, and there was no personal reason to react. But A.C. engages in a dialogue with newbies, and this is, from the pedagogical point of view, rather harmful. Please stop. Another example, for the rewriting this time: foldr (+) 1 [2,3] foldr (+) (1+2) [3] foldr (+) (1+2+3) [] 1+2+3 3+3 6 This derivation is pure rubbish. Read the definition of foldr, please, would it be the first time in your life??? The functional foldr is NOT tail recursive! And, actually, as EVERYBODY knows, Haskell is not a rewriting system. So, a good advice for J. Vimal: do whatever you wish, but avoid this fellow A. Coppin, since he leads you nowhere. Jerzy Karczmarczuk ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
[EMAIL PROTECTED] wrote: I will be impolite. If this were the first posting of A.C., I would suspect that he is pulling my leg, that his brilliant sense of humour surpasses my comprehension, so I should be filled-up with deep respect for such a wonderful mind. But enough is enough. Now, would it be really too much asking that - at least from time to time - Andrew Coppin think twice before saying things he - apparently - knows NOTHING about? OK. I get the message. I'm unsubscribing now... [How ironic the subject line suddenly seems.] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up! [OT]
[EMAIL PROTECTED] wrote: I will be impolite. There was no need to. Andrew Coppin wrote: OK. I get the message. I'm unsubscribing now... There was no need to. Please, let's keep haskell-cafe a friendly place, as it's always been. When someone posts inaccurate (or even wrong) facts: Attack ideas. Do not attack people. (Please!) Regards, Zun. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
You don't need to unsubscribe. Just avoid posting things that are totally wrong (at least without a warning). -- Lennart On 10/14/07, Andrew Coppin [EMAIL PROTECTED] wrote: [EMAIL PROTECTED] wrote: I will be impolite. If this were the first posting of A.C., I would suspect that he is pulling my leg, that his brilliant sense of humour surpasses my comprehension, so I should be filled-up with deep respect for such a wonderful mind. But enough is enough. Now, would it be really too much asking that - at least from time to time - Andrew Coppin think twice before saying things he - apparently - knows NOTHING about? OK. I get the message. I'm unsubscribing now... [How ironic the subject line suddenly seems.] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
On 10/14/07, Lennart Augustsson [EMAIL PROTECTED] wrote: You don't need to unsubscribe. Just avoid posting things that are totally wrong (at least without a warning). How would he know they're totally wrong ? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
On 10/14/07, david48 [EMAIL PROTECTED] wrote: On 10/14/07, Lennart Augustsson [EMAIL PROTECTED] wrote: You don't need to unsubscribe. Just avoid posting things that are totally wrong (at least without a warning). How would he know they're totally wrong ? Thinking before hitting the Send button might be a good first step, as well as refraining from giving the impression of certainty when one isn't actually sure. A little knowledge can be a dangerous thing, and it can be hard for newbies to evaluate the credibility of an answer. Cheers, Tim -- Tim Chevalier * catamorphism.org * Often in error, never in doubt There's no money in poetry, but there's no poetry in money, either. --Robert Graves ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up! [OT]
Roberto Zunino writes: [EMAIL PROTECTED] wrote: ... Andrew Coppin wrote: OK. I get the message. I'm unsubscribing now... There was no need to. Please, let's keep haskell-cafe a friendly place, as it's always been. Yes. I would add, friendly and USEFUL, as it's always been. It was not my intention of throwing away, anybody, and I didn't. I had no right to do such thing either. I just asked A. Coppin to think twice before submitting dubious statements, didn't I? I believe that it would be useful for the list if he stayed, and *asked questions*. My impoliteness was quite restrained... But, when J. Vimal threateneds us to throw away Haskell, complained about monads, and most people confirmed that the underlying theory is difficult, ugly, and useless, I began to read those postings with attention, since I disagree with spreading such atmosphere. And A.C. additionally wrote that all this theory has nothing to do with Haskell, and submitted three more postings, one more dubious than the other, I found that a warning seems suitable, not for him, but for his readers! Mathematics is beautiful and useful. The commutativity of some categorical diagrams can be translated into the optimization of Haskell constructs, say, showing that there is a canonical isomorphism between (map f) . (map g) and: map (f . g) etc. So, why dump the theory away, which suggests additionally that the conceptors of Haskell are irresponsible dreamers, living on some crystal mountain?... The language is not trivial to learn, that's it. If somebody feels discouraged, my own students often are, then the recipe is simple: ask CONCRETE questions, get CONCRETE answer. THEN generalize. But if some people offer general answers, they must be based on a real competence and experience, otherwise they easily become harmful. == David48 points out that if a list returns the reader to the docs which he has already seen, and which is poor, then it doesn't work at all. OK, then, once more, don't say I cannot understand monads, or rewriting, or whatever, but say plainly: I read XYZ in the ABC tutorial, and the example PQR remains too difficult. And say WHAT doesn't work. Go ahead, criticize *concrete* documentation, don't say that docs are lousy! Almost all Haskell documentation has been written by people who *beg* constantly for comments, for criticism; let's help them instead of shouting at them. Of course, the repeated, ever and ever again questions mean that one day it will be absolutely necessary to make a true FABQ, proposed a few times, and still in statu nascendi... Jerzy Karczmarczuk ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
On Sun, 14 Oct 2007, Andrew Coppin wrote: Vimal wrote: I like learning by comparison with other similar languages. This approach worked for me when I tried learning Python+Perl together. The nicer syntax and easier object-orientedness made me leave Perl behind and pursue Python. I also tried it for Haskell (Lisp+OCaml+Haskell together). This probably works quite well for mainstream programming languages (since they're all so similar), but is unlikely to work at all for Haskell (since, as far as I know, no other programming language on Earth is remotely like it - Miranda excluded). Even Lisp and Erland are nothing like Haskell, and they're supposedly based on the same ideas. I'm going to offer an opinion here that's likely to be controversial (in this forum): people new to functional programming shouldn't learn Haskell first. They should start with either Ocaml or SML first. If it makes it easier to accept this argument, you can consider Ocaml and SML as Haskell with training wheels. And that the original poster, rather than giving up on Haskell, should instead put Haskell on the backburner and instead learn Ocaml (which is likely to be hard enough). Then, in a year or two, start taking another swing at Haskell. The problem is that Haskell has a lot of big ideas that all come at you pretty much immediately. Learning a new language in a new paradigm is a lot harder than learning in a new language in a paradigm you already know. If you know Java or C#, it's not that hard to learn Python or Ruby, because you already know how to think in objects. The problem with going from a C/Java/Ruby paradigm to Haskell is that Haskell isn't just one paradigm shift, it's several all rolled into one: - Purely functional - Lazy - Monadic - Strongly typed Each one of these has a huge impact in how you think about problems and design programs- I'd argue about as large an impact as Objects have. These are all good things (well, I'd admit to not being 100% sure about pure laziness), and knowing how to think in these paradigms is definately a good thing. And the situation is worse with pure functional languages. When you move from, say C/Pascal/Fortran to Java/Ruby/Python, you don't have to learn new data structures and new algorithms. A doubly linked list is still just a doubly linked list, still has the same properties, and still has more or less the same implementation. In addition to learning Haskell, you also need to relearn basic computer science. You need to learn what a realtime lazy catenable dequeue is, how to implement it, and why you need one, all the while struggling with the syntax, type errors, and all the other problems trying to learning a new language. I mean, contemplate this trivial exercise for a moment: write a program that reads from stdin a series of numbers (one number per line), and writes out the sum of the last n numbers. This is a trivial problem, and I have no doubt that someone who knows Haskell better than I will reply to this email with a single line of code that does it. But just think for a moment the number of different paradigm shifts that you need to make to write this program in Haskell. I'm not saying that it's impossible to go directly to Haskell, I'm saying that it's just very very hard. Ocaml, meanwhile, is in many ways the C++ of the functional world. C++ was needed for object orientation to take off, because it allowed you to continue to program in plain old procedural C when you needed to get something done, and to play with OO concepts and ideas as you have the time/inclination/need. Then, once people became comfortable with objects and OO thinking, they were ready for the real OO languages. In a similiar fasion, Ocaml allows you to write old fasioned impertive code when you need to just get something working. And as you have the time/inclination/need to, you can start playing with more advanced functional concepts, like purely applicative data structures, lazy evaluation, and even monads. Brian ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
most widely-used programs (ex: web browsers, word processors, email programs, data bases, IDEs) tend to be 90% IO and 10% (or less) computation. This can make Haskell quite unweildy for solving these types of problems. On the otherhand, writing something like a compiler (which requires a small amount of IO - read a file(s), write results to a file - and a large amount of unseen computation - generating and optimizing code) is right up Haskell's alley. hey, compilers do nothing but IO! they read sources, print error messages or write object files and executables. there is really no need to do any unseen computation at all! unless there is some visible effect on the file system or programmer console, any such unseen computation is wasted, and should be optimised away. .. just kidding, of course?-) if compilers seem more suitable for haskell, it may be because they have been studied for a long time, and while throughput is important, noone is likely to argue that the core of compilation is about reading or writing files. the focus in writing compilers is on designing, implementing and manipulating the internal representations of the source and object code represented externally as strings of chars and bytes. applying the same reasoning to your most widely-used programs, we could say that their theory hasn't reached the same level as that of compilers (and so i'd remove data bases from your list, and editors are also reasonably well-understood). once their internal representations are better understood, programming again focusses on working with these internal representations (often called models), while IO reduces to a straightforward mapping from and to those internal representations that are closest to the external ones. claus ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
You're picking on Andrew Coppin? That's insane. He's got a sense of humour, and he's a lay (non-phd) person. Honestly, in one thread you've got Haskell is misunderstood! Its the greatest language in the world! Why does no-one use it and in another you're insulting one of the few non-phds who's interested in the language. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
On Sun, 14 Oct 2007, David Stigant wrote: However, most widely-used programs (ex: web browsers, word processors, email programs, data bases, IDEs) tend to be 90% IO and 10% (or less) computation. No, they don't. They look it, but there's always a fair amount of computation going on to decide things like what IO to do. For example, in a web browser the IO is in reading user input, rendering the display and interacting with the network - but page layout is computation, as is dispatching input. -- [EMAIL PROTECTED] Society does not owe people jobs. Society owes it to itself to find people jobs. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
Brian Hurt writes: I'm going to offer an opinion here that's likely to be controversial (in this forum): people new to functional programming shouldn't learn Haskell first. Great! So, there are at least two of us! They should start with either Ocaml or SML first. Or Scheme. Or *any* decent language, with functional tools. It is *exactly* what we tried to do with Python. Paying tribute to our pedagogical constraints, and teaching a language with a strong imperative taste, but using functional constructions as frequently as possible. Recursion, comprehensions, map/filter business (despite strong intentions of Guido V.R. of killing them...), etc. Also, higher-order functions, not so bad in Python, although sometimes curiously inefficient. But, anyway, splitting between the language and the basic techniques may be not so stupid. Hm. An Anglosaxon shouldn't say techniques may not be so stupid?... I agree with what Brian says next. But...: In a similiar fasion, Ocaml allows you to write old fasioned impertive code when you need to just get something working. And as you have the time/inclination/need to, you can start playing with more advanced functional concepts, like purely applicative data structures, lazy evaluation, and even monads. As far as the lazy evaluation is concerned, I would suggest then to jump to Haskell or to Clean, after just a few simple-minded exercices in other languages (the cons-stream, etc. in Scheme. Or, the generators in Python, which are in a sense lazy objects). Otherwise you will *never* get a taste of laziness. It is useful only if it is comfortable. Jerzy Karczmarczuk ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
Correction, I'm also very interested in Haskell, and I even don't have a bachelor degree :-) I'm a completely self-educated kind-a-guy... Anyway, IMHO Haskell rocks! A year ago I kind of started to hate writing code, and that after 25 years of coding in imperative and object-oriented languages. But thanks to Haskell, I found the vibes again! Cheers, Peter Verswyvelen Hugh Perkins wrote: You're picking on Andrew Coppin? That's insane. He's got a sense of humour, and he's a lay (non-phd) person. Honestly, in one thread you've got Haskell is misunderstood! Its the greatest language in the world! Why does no-one use it and in another you're insulting one of the few non-phds who's interested in the language. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
Or F#, if you know C#, which is the OCaml for the .NET world. Now I immediately went from C/C++/C# to Haskell, and yes, that was (is) hard. For me, the book Haskell School of Expression did it... All you need is a good book and lots of patience... Brian Hurt wrote: On Sun, 14 Oct 2007, Andrew Coppin wrote: Vimal wrote: I like learning by comparison with other similar languages. This approach worked for me when I tried learning Python+Perl together. The nicer syntax and easier object-orientedness made me leave Perl behind and pursue Python. I also tried it for Haskell (Lisp+OCaml+Haskell together). This probably works quite well for mainstream programming languages (since they're all so similar), but is unlikely to work at all for Haskell (since, as far as I know, no other programming language on Earth is remotely like it - Miranda excluded). Even Lisp and Erland are nothing like Haskell, and they're supposedly based on the same ideas. I'm going to offer an opinion here that's likely to be controversial (in this forum): people new to functional programming shouldn't learn Haskell first. They should start with either Ocaml or SML first. If it makes it easier to accept this argument, you can consider Ocaml and SML as Haskell with training wheels. And that the original poster, rather than giving up on Haskell, should instead put Haskell on the backburner and instead learn Ocaml (which is likely to be hard enough). Then, in a year or two, start taking another swing at Haskell. The problem is that Haskell has a lot of big ideas that all come at you pretty much immediately. Learning a new language in a new paradigm is a lot harder than learning in a new language in a paradigm you already know. If you know Java or C#, it's not that hard to learn Python or Ruby, because you already know how to think in objects. The problem with going from a C/Java/Ruby paradigm to Haskell is that Haskell isn't just one paradigm shift, it's several all rolled into one: - Purely functional - Lazy - Monadic - Strongly typed Each one of these has a huge impact in how you think about problems and design programs- I'd argue about as large an impact as Objects have. These are all good things (well, I'd admit to not being 100% sure about pure laziness), and knowing how to think in these paradigms is definately a good thing. And the situation is worse with pure functional languages. When you move from, say C/Pascal/Fortran to Java/Ruby/Python, you don't have to learn new data structures and new algorithms. A doubly linked list is still just a doubly linked list, still has the same properties, and still has more or less the same implementation. In addition to learning Haskell, you also need to relearn basic computer science. You need to learn what a realtime lazy catenable dequeue is, how to implement it, and why you need one, all the while struggling with the syntax, type errors, and all the other problems trying to learning a new language. I mean, contemplate this trivial exercise for a moment: write a program that reads from stdin a series of numbers (one number per line), and writes out the sum of the last n numbers. This is a trivial problem, and I have no doubt that someone who knows Haskell better than I will reply to this email with a single line of code that does it. But just think for a moment the number of different paradigm shifts that you need to make to write this program in Haskell. I'm not saying that it's impossible to go directly to Haskell, I'm saying that it's just very very hard. Ocaml, meanwhile, is in many ways the C++ of the functional world. C++ was needed for object orientation to take off, because it allowed you to continue to program in plain old procedural C when you needed to get something done, and to play with OO concepts and ideas as you have the time/inclination/need. Then, once people became comfortable with objects and OO thinking, they were ready for the real OO languages. In a similiar fasion, Ocaml allows you to write old fasioned impertive code when you need to just get something working. And as you have the time/inclination/need to, you can start playing with more advanced functional concepts, like purely applicative data structures, lazy evaluation, and even monads. Brian ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
On Sun, 2007-10-14 at 15:22 +0100, Andrew Coppin wrote: Vimal wrote: I think you have got a very good point in your mail that I overlooked all along ... Why was Haskell created? is a question that I havent tried looking for a answer :) To avoid success at all costs? (No, seriously. The basic idea was that there used to be about two-dozen languages like Haskell, but all developed by different people and all with different syntax and so on. So they wanted to create a single language suitable for teaching to students. You could say it's the Pascal of the functional world... Hey, maybe that explains the lack of success?) The first goal listed in the Haskell 1.0 Report is: It should be suitable for teaching, research, and applications, including building large systems. Haskell was never intended to be solely a teaching or research language. (You didn't necessarily say that, but it is a widely held and propagated misconception.) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
Correction, I'm also very interested in Haskell, and I even don't have a bachelor degree :-) I'm a completely self-educated kind-a-guy... That's true, and actually you and Andrew are two of the people whose opinions I respect the most. Well, I'll add SPJ to that list I guess. Anyway, IMHO Haskell rocks! A year ago I kind of started to hate writing code, and that after 25 years of coding in imperative and object-oriented languages. But thanks to Haskell, I found the vibes again! Oh, I wont deny Haskell is fun; wouldnt be here otherwise. Useful? Different question ;-) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up! [OT]
jerzy == jerzy karczmarczuk [EMAIL PROTECTED] writes: [...] jerzy But, when J. Vimal threateneds us to throw away Haskell, jerzy complained about monads, and most people confirmed that the jerzy underlying theory is difficult, ugly, and useless, I began jerzy to read those postings with attention, since I disagree jerzy with spreading such atmosphere. And A.C. additionally wrote jerzy that all this theory has nothing to do with Haskell, and jerzy submitted three more postings, one more dubious than the jerzy other, I found that a warning seems suitable, not for him, jerzy but for his readers! I'm an (almost) complete newbie to FP and for a beginner I don't see some right in myself to criticize theory being hard. I'm a CS guy without any background in Category Theory and related ideas, but when I see something elegant, I think I recognize it, and monads seem to be much elegant way of doing things than usual I/O. (And because of this elegance I couldn't persuade myself to learn OCam'l etc. first) Currently I can't say I understand monads, but as Von Neumann put it, Young man, in mathematics you don't understand things. You just get used to them. ;) jerzy Mathematics is beautiful and useful. The commutativity of jerzy some categorical diagrams can be translated into the jerzy optimization of Haskell constructs, say, showing that there jerzy is a canonical isomorphism between jerzy (map f) . (map g) and: map (f . g) jerzy etc. So, why dump the theory away, which suggests jerzy additionally that the conceptors of Haskell are jerzy irresponsible dreamers, living on some crystal jerzy mountain?... The language is not trivial to learn, that's jerzy it. If somebody feels discouraged, my own students often jerzy are, then the recipe is simple: ask CONCRETE questions, get jerzy CONCRETE answer. THEN generalize. I asked Paul Hudak a few days ago about an exercise in his Haskell SOE book and I got more than I expected. (Prior to that, I asked in #haskell and also got more than I expected, though not understood all of them ;)) jerzy But if some people offer general answers, they must be jerzy based on a real competence and experience, otherwise they jerzy easily become harmful. Being friendly is one thing, but being sensitive about the information is much more valuable IMO. I thank you for deciding to post this disclaimer instead of overlooking, which is perhaps the easier way. jerzy == jerzy David48 points out that if a list returns the reader to jerzy the docs which he has already seen, and which is poor, then jerzy it doesn't work at all. OK, then, once more, don't say I jerzy cannot understand monads, or rewriting, or whatever, but jerzy say plainly: I read XYZ in the ABC tutorial, and the jerzy example PQR remains too difficult. And say WHAT doesn't jerzy work. jerzy Go ahead, criticize *concrete* documentation, don't say jerzy that docs are lousy! Almost all Haskell documentation has jerzy been written by people who *beg* constantly for comments, jerzy for criticism; let's help them instead of shouting at them. jerzy Of course, the repeated, ever and ever again questions mean jerzy that one day it will be absolutely necessary to make a true jerzy FABQ, proposed a few times, and still in statu nascendi... I'm 27 years old and somehow programming for ~12 years in almost all major imperative languages. (I have some Scheme Lisp experience also.) As another poster mentioned, this language gave me long forgotten excitement of programming again. Though I feel myself too lazy to cope with problems (and obstacles in learning and changing mindset) sometimes, and I usually don't understand topics in this mailing list most of the time, I don't attribute these to difficulty of the language. This is my laziness, not Haskell's. If I would like to program in more understandable ways, I know there are lots and lots of other languages that I can use, but trying to come up with a solution and seeing how succint it can be amazes me in this language and I don't know if I can be a successful Haskell programmer (and write those haikus you write here and there), but at least I'll try to be and if I can't, this will be my laziness, not Haskell's. Thanks and best regards, E. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
G'day all. Quoting Derek Elkins [EMAIL PROTECTED]: The first goal listed in the Haskell 1.0 Report is: It should be suitable for teaching, research, and applications, including building large systems. Haskell was never intended to be solely a teaching or research language. (You didn't necessarily say that, but it is a widely held and propagated misconception.) I'd argue that you're kind of both right. The purpose of Haskell (i.e. Haskell 89) was to unify all of those Miranda-like systems into a single language that everyone could share. However, arguably the biggest imperatives for Haskell 98 was to remove features that would confuse undergraduates. Even though we may not like to admit it, H98 really is primarily a teaching/research language. If we were doing H98 today, I don't think that would happen. The research part is bigger and better than ever, but we seem to weight applications, including building large systems more highly than teaching now. Having said that, in retrospect, the clean break was probably for the best. H98 gave us a simpler core on which to add the glasgow-exts. There's some stuff from Haskell 1.3 that I miss, and I hope it will come back, but there's also stuff that we're better off without. Cheers, Andrew Bromage ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
Andrew Bromage writes: There's some stuff from Haskell 1.3 that I miss, and I hope it will come back, but there's also stuff that we're better off without. I have heard that a few times, not recently. This is really interesting, WHAT do you actually miss? For me, from the ancient times, what I regret, but just a tiny bit, is that (:) is not an operator as any other, but a syntactic construct. (Well, who cares, unless you try to make your own lists, with different precedence, etc...) Also, monadic comprehensions, which disappeared in order to remove too much of ambiguity... Anything else worth mentioning? What *negative* has been suppressed? Frankly, I regret the times when Mark Jones made his revolutions within Gofer, proposing constructor classes, etc. At that time we knew that Haskell was for the brave, not for people making money... Almost everybody was a newbie. Jerzy Karczmarczuk ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
G'day all. Vimal [EMAIL PROTECTED] quoted someone else as saying: Monads in programming seem to be the most mysterious notion of the century. I agree with the hair shirt talk on this. I found understanding monads no harder than understanding objects, starting from a comparable level of ignorance. I think the only difference is that object is a more accessible name than monad. instance WarmFuzzyThing IO where ... Cheers, Andrew Bromage ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
G'day all. Quoting Andrew Coppin [EMAIL PROTECTED]: I tried to use Wikipedia to learn about how to build digital filters... this was a disaster. There is almost no useful information there! :-( That's not my experience. I didn't really understand Kalman filters until I read the Wikipedia page. It's better than most of the tutorials out there. (I think you have to luck out with the right topic.) Cheers, Andrew Bromage ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
G'day all. Quoting [EMAIL PROTECTED]: I have heard that a few times, not recently. This is really interesting, WHAT do you actually miss? Off the top of my head, from H1.4, I miss: - MonadZero (a lot) - Some of the monad/functor-overloaded functions (quite a bit) - Record punning (slightly) For me, from the ancient times, what I regret, but just a tiny bit, is that (:) is not an operator as any other, but a syntactic construct. I agree with that in principle; it's unfortunate that lists are built in as much as they are. But I can't say I really miss this. Also, monadic comprehensions, which disappeared in order to remove too much of ambiguity... Five years ago, I would have agreed. I'm over that now, and do-notation is more useful. Anything else worth mentioning? What *negative* has been suppressed? I mentioned the un-generalising of map above. That probably needs some justification. I think that the best evidence of why this was a mistake is the fact that many modules implement a namespace-overloaded map. Data.Map.map springs to mind, but there are others. People want to write map instead of fmap. We could have come up with an alternative name for the list-version of map and not showed map to newbies. (Having said that, some of the un-overloading was good. I'm happy, for example, to reserve concat for lists and use join for monads.) Cheers, Andrew Bromage ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
Or you could just use Data.Sequence and brows the code at your later leisure, right? Better yet, you could forget about optimal datastructures until you learned how to do toy problems with just plain lists. --S On Oct 14, 2007, at 2:12 PM, Brian Hurt wrote: And the situation is worse with pure functional languages. When you move from, say C/Pascal/Fortran to Java/Ruby/Python, you don't have to learn new data structures and new algorithms. A doubly linked list is still just a doubly linked list, still has the same properties, and still has more or less the same implementation. In addition to learning Haskell, you also need to relearn basic computer science. You need to learn what a realtime lazy catenable dequeue is, how to implement it, and why you need one, all the while struggling with the syntax, type errors, and all the other problems trying to learning a new language. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
On 15 Oct 2007, at 2:59 am, Vimal wrote: I like the quote found on this site: http://patryshev.com/monad/m- intro.html quote Monads in programming seem to be the most mysterious notion of the century. I find two reasons for this: * lack of familiarity with category theory; * many authors carefully bypass any mention of categories. It's like talking about electricity without using calculus. Good enough to replace a fuse, not good enough to design an amplifier. /quote It is true that Haskell Monads are inspired by category theory. It is also true that all the operations you need for something to be a category theoretic monad are available for Haskell Monads. HOWEVER You don't need to know that. Many Haskell programmers not only don't understand anything much about categories, they will never understand anything much about categories, and it doesn't matter. (After years of study, I can now get *to* chapter 3 in the typical introduction to category theory* book, but not *through* it.) The really amazing thing about the IO Monad in Haskell is that there *isn't* any magic going on. An level of understanding adequate for using the I/O and State monads stuff (that is, adequate for practically anything analogous to what you might do in another language) goes like this: A type constructor that belongs to the Monad class can be used to sequence actions over some kind of hidden state. Each of these actions has an effect and a value. For example, getChar has the effect of reading a character from standard input, and the character it read as its value. For example, putChar x has the effect of writing a character to standard output, and () as its value because there isn't anything else useful to return. All monad instances must provide fail msgmsg is an error message; this reports an error. return valuean action with value as its value and no effect act1 act2 the effect of (act1 then act2) and the value of act. THIS IS JUST LIKE SEMICOLON IN TRADITIONAL LANGUAGES. act1 = actf2the effect of (act1 then (act2f x)) with the value of act2f x, where x is the value of act1. Each monad also typically comes with a function that takes an action and an initial state and performs the action and returns its value. That function's name usually starts with run. For the IO monad, the hidden state is the state of the world, including I/O devices, and the run step is done just outside your 'main' function. In order to have an I/O action performed you should ensure that it is chained into the sequence actions starting from main and linked by and = . That's really all you have to know. The I/O actions in Haskell look uncommonly like C, and if you can do I/O in C you *can* do I/O in Haskell without even knowing how to spell 'Category Theory'. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up!
On Oct 14, 2007, at 22:54 , Richard A. O'Keefe wrote: The really amazing thing about the IO Monad in Haskell is that there *isn't* any magic going on. An level of understanding adequate for using the I/O and State monads stuff (that is, adequate for practically anything analogous to what you might do in another language) goes like this: (...) I like an explanation dons gave once the best: A Monad is a programmable semicolon. That pretty much sums it up, nice and simple. Everything else is just scaffolding. -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] [EMAIL PROTECTED] system administrator [openafs,heimdal,too many hats] [EMAIL PROTECTED] electrical and computer engineering, carnegie mellon universityKF8NH ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up! [OT]
On 15 Oct 2007, at 5:41 am, [EMAIL PROTECTED] wrote: But, when J. Vimal threateneds us to throw away Haskell, complained about monads, and most people confirmed that the underlying theory is difficult, ugly, and useless, I began to read those postings with attention, since I disagree with spreading such atmosphere. And A.C. additionally wrote that all this theory has nothing to do with Haskell, and submitted three more postings, one more dubious than the other, I found that a warning seems suitable, not for him, but for his readers! I hope we can agree on several things here: (1) The mathematical background of Haskell is one of the things that makes Haskell a beautiful and useful programming language. It may even be one of the most important factors. (2) The mathematical background of Haskell is extremely important for implementations. Some important data structures and techniques are practical in large part because of the kinds of optimisations that are only straightforward in a language that has such foundations. (3) Beginners do not need to understand all the mathematics behind Haskell to use it. I really really hope we can agree on the next two points: (4) It is not unfair to describe Category Theory as The mathematical study of sound analogies between mathematical structures; it leads to concepts of great generality and power, and encourages a consistent use of terminology which makes it easier to transfer ideas and techniques from one area of mathematics to another. It's about *consistently* pushing generality rather hard. (5) Precisely because it seeks generality, category theory seems difficult to concrete thinkers. And books on category theory tend to be extremely fast-paced, so ideas which are not in themselves particularly esoteric (which may in fact be eminently practical) tend to be presented in a way which people trying to study by themselves have trouble with. So people can be scared off by what _ought_ to be a big help to them. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up! [OT]
G'day all. Quoting Richard A. O'Keefe [EMAIL PROTECTED]: (5) Precisely because it seeks generality, category theory seems difficult to concrete thinkers. And books on category theory tend to be extremely fast-paced, so ideas which are not in themselves particularly esoteric (which may in fact be eminently practical) tend to be presented in a way which people trying to study by themselves have trouble with. So people can be scared off by what _ought_ to be a big help to them. I agree, but I don't think it needs to be this way. Books on category theory tend to be written for mathematicians or computer scientists who already grok the things that need generalising, even understand in a general sense how they're similar, and really just need to learn the language to express what they already know. In one respect, this makes sense (you learn the concrete, then you learn how to abstract away the details), but it also raises the barrier to the point where in learning mathematics, you're really learning history. Mathematics isn't immune from this, of course. Many scientists in disparate fields have complained that textbooks for their fields are really history books in disguise, and the material is more confused and tedious than it needs to be as a result. Example complaints: http://insti.physics.sunysb.edu/~siegel/history.html http://jchemed.chem.wisc.edu/journal/issues/1998/jul/abs817.html Cheers, Andrew Bromage ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] On the verge of ... giving up! [OT]
G'day all. Quoting Brandon S. Allbery KF8NH [EMAIL PROTECTED]: I would really like to see category theory for the working *non*mathematician. It's pricey, but your local university library probably has it: http://www.cambridge.org/catalogue/catalogue.asp?isbn=9780521478175 Cheers, Andrew Bromage ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
